flooding

[Dw07u]

Guys, I've had my bike at a couple places now, carbs have been checked and all that like three times, but it still gives me the same problem... If it stands a while, like more than a day or two, it seems flooded, then only way to start is a rolling start, at which time it spews fuel out the exhaust. I do close the tap asap when I stop... what can cause this flooding, please, cuz everytime i take it in the guys say my carbs are gunky and needs cleaning, costing me a fortune... plz, help, gonna fix the thing and sell it... or just sell it, works fine if it gets used everyday...

PLZ HELP! I have already spent a arm and a leg on this machine, runs 100%, on a warm start it starts right away, but I can't go on like this, it seems like its been going into the shop every odd month, they fix some things, change the battery and clean the freaking carbs cuz its gungkd with old fuel... it runs fine a week or so, riding it every day, then over the weekend or a couple rainy days... it just acts up again, push start it and if it does start with the first couple of tries, it runs well...

I'm getting depressed here, I was honestly thinking of selling everything I own and go live in the bush, since I spend nearly all of my part time, student salary on fixing the thing, instead of buying a new helmet and tires like I want...

[sgtslag]

I'm not an expert, but it sounds like the floats are stuck, allowing gasoline to flow freely.  There should also be drain tubes for overflowing gasoline to run down to the ground, beneath the bike -- one tube on each carb?

If the Shop has cleaned the carbs already, they should stand behind their work, and fix it for free...  If they're trying to charge you, repeatedly, for the same problem, then they're definitely being dishonest.  Hopefully one of the more knowledgeable folks will chime in soon with more definitive answers for you.  Cheers!

[rich]

I'm not sure if you're having starting problems or carb problems.

If your carbs were causing the flooding, due to dirty, worn needles and seats or floats that are bad or out of adjustment, you should see gas leaking out from the overflow tubes at the bottom of the carbs when you leave the fuel on and the engine is off. Here's a thread with a lot of good info on trouble shooting that kind of problem - http://honda-cb750-s.456789.n3.nabble.com/i-d-love-to-ride-again-various-questions-issues-td955576.html

If that's not the case, then maybe the flooding happens when you try and start it. If you're cranking on it enough to run the battery down (you said you have to push start it), a lot of fuel is getting drawn in and it would appear flooded. I know I've done that to mine because I didn't notice the engine run switch was set to "off" and I kept cranking it anyway.

Next time you go to start it, after it's sat a couple of days, just pull the choke and hit the starter. Don't goose the the throttle when you're trying to start it. You might want to try a fresh set of plugs, repeated flooding can foul them.

[shinyribs]

I agree with SgtSlag and Rich.I would add though,when i start mine it never likes full choke,i usually only close it about 80%.And i open the throttle just a wee lil bit.

Good luck to ya man,i hope you fix it

[TOOLS1]

I agree with every body else, but will add, Change, or rebuild the petcock, and add a fuel filter.
TOOLS

[Dw07u]

Thanks guys, will check it out...

The petcock, how hard would it be to replace, and how would I go about testing the thing?

It runs fine once started, which tells me it's probably not the plugs, and like i said, I turn the petcock to off position immediately...

The carbs have got needles and seats replaced a couple months ago, and the carbs have since been cleaned and synchronized about three times...

all I can think now is that the petcock or something is letting fuel through, or when i try start it, it just lets way too much fuel through, but if thats the case it should happen everytime, not just after standing a couple days?

Anyway, If it does end up being the petcock, can i just use some sort of clamp to clamp the fuel line shut? untill i can get the petcock redone/replaced?(obviously taking it off when I go riding...)

Oh and tell me if this makes sense... if the petcock is on the off position, suction should prevent any more fuel pouring into the carbs right?

Regards

[TOOLS1]

To check the petcock, turn it to off. Then remove the fuel line from the carb, or from the petcock, and install another piece of fuel line onto the petcock. Put the end of the fuel line into a container, and wait to see if the container fills with gas. If it does then the petcock is bad.
I suppose, you could squeeze the fuel line with a pair of vice grips to shut it off.
TOOLS  

[sgtslag]

Clamping the fuel line will work for a while...  Then the hose will crack, and gasoline will poour out on the ground.  You need to fix it properly, and safely.  

You stated that the carbs have been synchronized three times...  Will the shop warranty their work?  If not, run, don't walk, to another shop who will stand behind their work.  I assume, of course, that you made them aware of the nature of the problem, and that it is a recurring issue?  That level of dis-service deserves to be slapped silly, and advertised loud and wide, to warn others away from them.

The petcock is a simple valve.  Gasoline flows down from the fuel tank, through the hoses, past the shutoff-valve/petcock, into the floats, then into the carbs, all by gravity.  There is an accelerator pump in the carbs to pull it out of the floats, but there is no fuel pump, like what you find in modern car's fuel tanks (modern fuel injection systems pump gasoline into the injectors at around 40 PSI).  Your bike's gasoline flows slowly, under very little pressure, gravity feed only.  The gas cap has a valve in it, which allows air to fill the gas tank, as gasoline flows out, which prevents a vacuum from forming.  The only vacuum within the fuel system, is present within the engine, and the carbs, generated by the pistons, and the venturis.

Best of luck.  Cheers!

[Re-run]

Give us the procedure on how you start your bike. That might add to the equation.
As tools said, check the petcock. Make sure it actually shuts off. You should also check your float levels and your overflow tubes. Get some clear hose and fit it to the bottoms of the bowls and angle it up. Do all 4, then open the bowl drain screws. Check your level. Now leave it like this and turn off the petcock.
Check it a while later and see if the level has gone up. Oh btw, your fuel level should not be higher then the bowl. If it is, your floats need to be adjusted. This is the case on my 78K and I suspect it will be the same for your dohc.

If fuel height and the petcock check out, I would move on to the jets and your idle mix settings.
On my 78, I had and issue with my #2 running very rich at idle. Found out the idle jet was clogged and it was sucking through the main jet. You could be having something similar. Engine is just pulling to much fuel when starting.

Seems that it may be time to download the manual, grab a couple phillips style drivers, a 10 & 12mm wrench, pliers, and some rags. Pull of the carbs and check them jets out. Also check any gaskets for leaking and diaphragms for cracks. As long as your do not pull out any slides, you do not need to re-sync.
Just pull the jets and make sure you can see light through every single hole. Any possible blockage should be dealt with using a thin strand of copper wire or the #1 string on a guitar. Gently poke around and through each hole and follow up with CAREFUL blasts of carb cleaner.
And as the sarg said, find a different shop if you need help yet.

[Dw07u]

I'm going to crap on the guys who did it last, as he did tell me the petrol seemed to gunk up in the carbs. He assured me the bike was fine, and I paid him, obviously he did not bother to check why the petrol was gunked up... I'm not much of a petrol head, and would prefer if some1 else fixed it, I'm going to speak to the owner of the shop and get the bike fixed free of charge, I mean, i'm sure it's just something small like all the stuff you guys mentioned...

Oh and I did check the petcock, it is not shutting off properly...

As far a s my starting procedure goes.... level the bike, either by getting on it or center stand... turn on ignition and put in neutral... slightly pull the choke, not all the way,turn petcock to the on position and grab the clutch, press the starter button... (obviously while the cutoff switch is in the correct position). This has worked perfectly in the past, like for the first three moths I had the bike, and since then everytime I got something fixed, it works too... Now this bike has givin me alot of hassles, but I believe that this fuel problem is probably the major cause of most of the problems I have had... Thats to even say if these problems were actually problems...

I really appreciate all your advice, but living with my parents still, my dad would rather sell the bike at a major loss than have me tinker with it... And I know it's my bike and all, but I respect my dad and his wishes... So Next week I will be speaking to that owner of the shop and getting this sorted out... I have the bike up for sale, although i do not wish to sell it, firstly because it's not running 100% and secondly I will lose so much money on it... thirdly, it's my bike, and it rides like a dream, I don't want to lose it to some stupid problem that no one has thought of yet... I sometimes get the idea these workshops only look for big problems where they can make the most money out of... because if it is the petcock, its a small job, and easily solved with the right know how...

I just get so enraged when I have to go somewhere and the thing does not start after just having spent ,more than a months salary on it and being assured the problem has been solved...

Thanks again for all your input and advice...

[sgtslag]

Petrol can go bad ("gunk up") after only one month of sitting in a gas tank.  There are two inexpensive things you can do to avoid this:  1)  Add a gas preservative, like Sta-bil, or SeaFoam, to the tank (SeaFoam will also dissolve varnish within the gas tank, and fuel system, absorb water, and preserve gasoline up to one year); 2) install an inline fuel filter, preferably something better than the OEM metal screen sitting on top of the petcock, inside the gas tank...

Check your petcock assembly for the screen:  mine was missing, and I did not learn of it until I'd had the bike for more than a year!  Your "gunking up" problem may be crud clogging the carbs:  rust can form within the fuel tank, and bits of it can flow down into the carbs, and clog them -- a paper fuel filter will prevent this.  I installed a small, inline filter, just after the petcock, in the hose carrying gasoline to the carbs.  They typically run around $2-$4, in an auto supply store.  The paper filters are just fine, but be sure to get one that is as small as possible, preferably a disc type -- that hose is relatively short, so there is not enough room for a filter that adds 2"+ to the fuel line, unless you add more fuel line (not a great idea, as it has to go somewhere, and you need to be careful it doesn't get pushed against anything sharp, or hot).  Best of luck!  Cheers!

[Lucky 1]

It is too bad you cannot get competent help on your bike from a shop.

It needs new float needles and a new fuel filter. Clean the tank out too.

Do not adjust the old floats- just put in new float needles.
Many of these shops now just have young mechanics and
all they want to do is pull out a laptop computer .

Many of them have never rebuilt or looked at a carb. It is a real shame.
Before you give it to ANYONE to work on make sure they know how to work on a carburator.
ASK them directly. "Have you ever worked on a motorcycle with a carburator?"

[Piute]

 Ya-No My floats were all upside down. I had to look at the picture A few times before it clicked.Hey they looked right if you didn't know...........Piute.............

   Hey Lucky you must be by me cause went in to get a tire mounted(Perormance Cycles)and ask if they could sink my carbs "" O we don't work on old bikes "" what the guy behind the counter said
Then my smart a?? Said "So you only have a programmer and a tire changer back there "grabbed a few free lic frames and left.

[Dw07u]

LOL guys, anyway, well yeah I had it at Honda and the mechanic there wasn too young, knew his stuff, could tell(also I think he did change the needles and seat)... but that was a longish(5 or so months) time ago, Honda is really expensive here, so I phoned another Honda dealer that everyone raves about, and the manager told me I'll pay through my nose if I took it in to them, but he referred me to some other ppl who "specialize in older bikes"... I just think they were too lazy to really troubleshoot the problem, and ignored it as the regulator was their main concern at that moment... Although The issue at hand I did mention and ask for to solve... not to mention I asked him to check the tank too, since The problem seems to be more pertinent when i have had it on reserves that day... He said he checked it... bt i just think he switched to reserves and let it run a while... I dunno, I'm just so gatvol, in this countries currency I am paying these okes good money... really good money... I mean, My bike services because of this problem is more than my sister's Peugeot services was... honestly, and two weeks after every service the problem reoccurs... Anyway gents, I'm going away for the weekend to spend some time with nature and some friends! Hope you all have a happy and prosperous new year!!!!!

[shinyribs]

Honda put a petcock on these bikes for a reason.If it wasn't absolutely necessary they wouldn't have spent the time and money to install one on the bike.I know some guys will say that their bike does fine without ever shutting off the gas,and they are probably right.But yours may be one of those bikes just doesn't want to let you get away with that!If your petcock is bad ( i think you said it was) and it is flooded after sitting for extended periods,then it sounds like you may have found your problem.A fast,easy and almost free way to check this is to go get an inline valve for your bike.Put it in the line directly after,and as close to the petcock as possible.Operate the bike as normal,and don't change anything else.That will give you a positive fuel cut-off when parked for extended periods.If the problem goes away then you found it.Just a thought.

I REALLY hope you are able to keep your bike if thats what you want.Best of luck to you

[victor]

HI there! I just chanced upon this group since I was surfing the net for solving the same problem. As I read thru you guys discussion, I just cant help to say that all of the advices on this problem are correct!! My bike is a Honda CB 1000 95. Its got four carbs. Your problem is exactly like man. Let me tell you what I did. I kept of bringing down the carbs its almost 10 times now!!! I did all that was necessary. Cleaned it with a can of carb cleaner, stripped the carbs to its last nut and bolt. Used a high pressure hose with a fine nozzle and blew high pressure air in all of the holes and passages ways that I could see. this included the jets, air/fuel mixture needle hole, drain screw etc. I even tried using a guitar steel string as one of you mentioned. As I did all of those I couldn't believe that the problem is still there!!! It floods the intake manifold with a pool of gas. I saw this when I brought down the carbs and there it was a pool of gas in the intake. Before I knew the problem sometimes I would force start it and a loud snapping sound would breakout as it tries to turn over. I used to turn the rear wheel to get the pistons moved so as the pool of fuel would sink down. this flooding was in fact verified as I took out the fourth spark plug and switch start the bike just for a few seconds. As it started, I could feel the left over gas spewed out from the hole!!! Dont get so frustrated, I felt exactly what you have felt, even of selling the bike. But dont! The problem can be fixed. Its just the one of those holes in that carbs that still needs to be unclogged. Once you correct it, your bike would bring you anywhere you wish and have fun together till you last ridding days!! So far as I observe her, and start her in the morning she appears to be well again. I just hope this flooding will be over. Thanks for your time gentlemen.
Live to ride and ride to live!!!

[torsoman76]

Cheers everyone. Just joined the forum and recently purchased my first Honda. 1977 CB750K. I started the bike a few times over the last week and it started fine each time. Today, I went to take her out and after the first start with choke pulled she started. When I pushed the choke in she stalled. This happened twice and than I noticed fuel on the ground under the bike. I let the bike sit for a few minutes and started the bike again, but when I pushed the choke she stalled again. Now the bike wont start. When I push the starter button it just makes a ticking noise. ????? Please help me folks, Thanks. Oh, the petcock does leak a little. Thanks

[motogrady]

Anyone check to see if there's contaminant in the tank?

Maybe install a 5 dollar clear plastic inline fuel filter?

Tickin noise, sounds like someone ran the battery down to nothing trying to start it.

[icerigger]

If your petcock leaks, then any problem with the float valve/seat or cracked overflow tubes will spew fuel out the overflow hoses. Make sure these are routed correctly. Some people (PO of my bike for one) will route the hoses up over top of the airbox to mask a problem when selling the bike and you end up with fuel running into the head and down into the cylinder.

[victor]

To correct the flooding: these are the MUST things to do.  1. Buy new valve floats 4 of them. 2. Bring down the carbs and open up all the four carbs. 3. Spray all holes that you see with one can or two cans of carb cleaner. 4. Unscrew the all the jets that you could unscrew and Spray each jet nozzles front and back. speciall check the fine jet holes which is as small and thin as a guitar string. In fact get a guitar string no. 1 steel wire for probing into the fine thin holes of each jet. 5. Before assembling the parts back together with a high pressure air hose, blow into all the orifices one final time. 6. Bring down the tank and open up the pet cock with the gas filter in it. I am sure your tank will be full of rust. Clean you tank by drying it first and shake it and blow high pressure hose to get rid of rust and crud  and all other sediments. Bear in mind you need a good brand new fuel filter to filter out all other possible sediments that might be sucked up into the carbs. What I did I improvise by adding another secondary fuel filter along the fuel line before it gets into the carb. This will clear all other possible sediments that would clog your carbs!! Good luck. Enjoy the process it will reward you of years of riding!!!